PPAPI: Purposely leak ProxyLock, fix shutdown race

ppapi/thunk/enter.cc

Index: ppapi/thunk/enter.cc
diff --git a/ppapi/thunk/enter.cc b/ppapi/thunk/enter.cc
index bd955b2ca8f81d0fc3177f1a586c42f3b6c525e5..47889dd15776c7b4feadada713b8496f835611bb 100644
--- a/ppapi/thunk/enter.cc
+++ b/ppapi/thunk/enter.cc
@@ -29,14 +29,6 @@ namespace thunk {
 
 namespace subtle {
 
-void AssertLockHeld() {
-  base::Lock* proxy_lock = PpapiGlobals::Get()->GetProxyLock();
-  // The lock is only valid in the plugin side of the proxy, so it only makes
-  // sense to assert there. Otherwise, silently succeed.
-  if (proxy_lock)
-    proxy_lock->AssertAcquired();
-}
-
 EnterBase::EnterBase()
     : resource_(NULL),
       retval_(PP_OK) {